The Summer Triangle is still nicely visible in the South at about 10 pm. Today the Moon low and Saturn ever lower in the South West. The autumn constellations Taurus, Auriga, Gemini and Orion are visible just before Sunrise. Mars is visible just before Sunrise.
Due to the Full Moon on Saturday 29 August, it will be hard to observe deep sky objects and as well the Milky Way. Try though just after midnight and get yourself to a dark place.
Mercury is not visible and too close to the Sun. Venus is close to the Sun and best seen from 5.15 am to 6 am in the constellation Cancer. The planet is getting visible earlier towards next week while it moves further from the Sun. Mars is best seen from 4 am to 5.30 am in the constellation Cancer. Jupiter is not visible today, but by next week further from the spot and hardly visible around 6 am. Saturn is the only planet, though low on the horizon, visible in our night skies. Best seen from 8.40 pm to 10.50 pm in the constellation Libra. You will need a small telescope or binocular to spot the planet Uranus. The planet is best seen from 11.10 pm to 4.15 pm in the constellation Pisces.
The Sun rises today at 6.05 am in the East North East and sets in the West North West at 8.11 pm. Sunsets gets in a week's time 12 minutes later and at Sunset 17 minutes earlier. Days are getting shorter.
Wednesday 26 August
Today in 1959 the popular Mini car was introduced by the British Motor Corporation. The Mini car is still successful over five decades later.
At 9.15 pm the Moon is close to the star Rho1 in the constellation Sagittarius. The limb separation is 3° or 6 lunar diameters. Altitude of the Moon is 18° and the Moon phase is 88%. Be aware that the Sun is not long set and is at -9°.
At 11.02 pm the planet Jupiter is in conjunction with the Sun. This is not visible. Jupiter furthest distance is at 1.13 am. The distance to the Earth is 6.399 AU. One Astronomical Unit (AU) is the distance Sun to the Earth.
At 11.58 pm a flare can be seen in the West South West at 23° in the constellation Ophiuchus. After midnight, at 1.13 am the planet Jupiter is at its farest distance. The distance to the Earth is 6.399 AU.
Thursday 27 August
Today in 1784 James Tytler made the first balloon ascent in Britain in a hot-air balloon at Edinburgh Scotland.
At 9.10 pm the Moon is close to the brighter star Dabih. The limb separation is 3°or less than 6 lunar diameters. The altitude is 18° and the Moon phase is 95%. The Sun is 9° under the horizon and the sky is still bright.
A flare at 9.40 pm in the East North East at 77° in the constellation Cygnus. After midnight at 2.55 am a very bright flare in the West North West at 25° in the constellation Hercules.
Friday 28 August
Today in 1837 the pharmacists John Lea and William Perrins of Worcester began the manufacture of Worcester Sauce. Its origin was accidental. The two Worcestershire pharmacists were asked to make a sauce using a recipe Lord Marcus Sandys, governor of Bengal, had brought from India. The result had a harsh, unpalatable taste. The batch was stored in their cellar and forgotten for a year. At that time, after an aging process, a chance tasting for the sauce was now tasty.
It is flare night ... At 9 pm a bright flare in the North at 30° in the constellation Camelopardali. Another bright flare at 11.37 pm in the North East at 30° in the constellation Perseus. Just before midnight, at 11.54 pm again a bright flare in the West South West at 21° in the constellation Ophiuchus. A very bright flare at 4.18 am in the West at 55° in the constellation Lacerta.
Venus is in conjunction in Right Ascension with Mars at 6.19 am. Venus is 9.4° separated from the center of Mars.
Saturday 29 August
At 7.35 pm the Moon is full. This is the 2nd biggest Full Moon of the year. Former larger Full Moon was at 10 August 2014. Next larger full moon is at 28 September 2015. This is also called a Super Moon. This Super Moon is the first out of 3 in 2015. The Moon reaches Full 20 hours from perigee. This Full Moon was known by early Native American tribes as the Full Sturgeon Moon because the large sturgeon fish of the Great Lakes and other major lakes were more easily caught at this time of year. This Moon has also been known as the Green Corn Moon and the Grain Moon. This is also the first of three Super Moons for 2015. The Moon will be at its closest approach to the Earth and may look slightly larger and brighter than usual. The Moon rises at 7.45 pm and the Sun sets at 8.04 pm.
At 7.40 pm the planet Mercury is in aphelion, the furthest away from the Sun. The distance to Sun is 0.4667 AU.
We have two flares to finish off the night star gazing. One very bright at 2.52 am in the North West at 22° in the constellation Hercules. And a second at 4.12 am in the West at 53° in the constellation Lacerta.
Sunday 30 August
Today in 1844 the British amateur astronomer Francis Baily died in London. He was co-founder of the Royal Astronomical Society, of which he was president for years. Baily described the after him called Baily's beads. He was born in Newbury Berkshire on 28 April 1774.
At 4.28 pm the Moon Perigee, or furthest away. The distance of the Moon to the Earth is 358282.7 km.
Two flares for the evening. Once at 8.48 pm in the North at 33° in the constellation Camelopardalis. And the second at 11.52 pm in the West South West at 19° in the constellation Ophiuchus.
Monday 31 August
This is a UK bank holiday! Today in 1900 the Coca Cola was first sold in Britain in the basement restaurant of Spence's department store, a silk merchant and general goods store at St Paul's Churchyard in London. It later went on regular sale through soda fountain outlets, which included Selfridges and The London Coliseum.
A rather bright flare at 11.54 pm in the West South West at 16° in the constellation Hercules. Another of the same brightness after midnight at 2.49 am in the North West at 19° in the constellation Hercules.
After midnight, at 4.35 am the distance planet Neptune is in opposition, which means the planet is on the other side as where the sun is positioned. The distance to the Earth is 28.953 AU. Due to the brightness (7.8 mag) you will need a good telescope to observe.
At 6.04 am the planet Venus is in conjunction with Mars. Both are about 9° separated. Use binoculars to watch early morning at dawn.
Tuesday 1 September
Today in 1859 a Solar flare was observed for the first time by the astronomer Richard C. Carrington. He reported his description of a singular appearance seen in the Sun in the Monthly Notices of the Royal Astronomical Society in 1860.
At 7.26 pm the Equation of time is zero. The apparent Solar time is now equal to the mean Solar time. Just that you know ... Sun set is at 7.57 pm in the West North West.
Flare night! At 9.37 pm in the East at 72° in the constellation Cygnus. At 10.23 pm a very bright one in the North east at 36° in the constellation Andromeda. At 11.58 pm a very bright flare in the West at 14° in the constellation Hercules. Once after midnight at 0.03 am in the West at 12° in the constellation Hercules. A very bright one at 5.38 am in the South South West at 65° in the constellation Aries. And last a bright flare at 5.40 am in the South South West at 65° in the constellation Aries.
Wednesday 2 September
Today in 1752 was the last day of the Julian calendar in Great Britain, Ireland and the British colonies, including those on the East coast of America. Eleven days were skipped to adopt the Gregorian calendar, designed to realign the calendar with equinoxes. Hence the following day was 14 September.
At 6.50 pm the planet Venus is close to Mars and only 9° separated. Both planets to watch with binoculars in the early morning close the Sunrise in the West.
At 10.17 pm a flare in the North East at 36° in the constellation Perseus. A second one, brighter at midnight at 0.01 am in the West at 12° in the constellation Hercules. And one more flare at 3.57 am in the West at 48° in the constellation Pegasus.
Get in touch with me via www.patrickpoitevin.weebly.com if you need more information.
Ashbourne SKY WATCH week of Wednesday 26 August 2015
Size does matter ... in the Sky!
How often do we hear that the Moon is so big in the sky? Or as in last week's story, Mars is as big as the Moon in the sky? This week's Full Moon is once more a Super Moon.
Sizes are measurable and can be expressed in a dimension. How come, although the Sun is much bigger that the Moon, that we can have eclipses, or that the Moon just covers the Sun? How come we see the constellations in the shape and format we see them now but that the actual stars do not have any relevant connection to each other? So many questions about sizes and distances
The angular diameter or apparent size is an angular measurement describing how large a sphere or circle appears from a given point of view. In the vision sciences it is called the visual angle. The angular diameter can alternately be thought of as the angle an eye or camera must rotate to look from one side of an apparent circle to the opposite side.
We can estimate the sizes with a stretched hand. Some basic tricks for estimating distances in the sky. Stretch your arm, and …
• Spread your little finger and thumb and the distance in the sky is 25 degrees.
• Make a fist and the width of your fist gives the distance in the sky is 10 degrees.
• Spread your little finder and pointer and the distance in the sky is 15 degrees.
• Keep your 3 fingers next to your pointer together and the distance in the sky is 5 degrees.
• The width of one little finger in the sky is 1 degree.
In values ...
Degrees are subdivided as follows:
• 360 degrees (°) in a full circle
• 60 arc-minutes (′) in one degree
• 60 arc-seconds (″) in one arc-minute
In astronomy the sizes of objects in the sky are often given in terms of their angular diameter as seen from Earth, rather than their actual sizes. Since these angular diameters are typically small, it is common to present them in arc seconds. One arc second is 1/3600th of one degree.
The horizon is 0 or zero degrees high, right above it is 90 degrees high, and right in between it is 45 degrees. So far about altitudes or heights in the sky.
The total circle around you, all around the horizon, it is 360 degrees around. The wind directions are each 90 degrees from each other. The positioning on the horizon is called the azimuth. North is azimuth 0 degrees. Moving clockwise on a 360 degree circle, East has azimuth 90°, South 180°, and West 270°.
The elongation is the distance of an object to the Sun. The object can be a planet, a star, Moon or even an optical object as a Sundog, etc. The closer the distance to the Sun, the smaller the value.
The height of the Sun?
The elevation is 0° at Sunrise and 90° when the sun is directly overhead. If the Sun altitude is expressed as "-" or minus, it means the Sun is under the horizon. Important for night observations as the Sun still produces light. It is dawn or dusk when the Sun under the horizon. Astronomically, sunrise occurs for only an instant. It is the moment at which the upper limb of the Sun appears tangent to the horizon. Twilight is the period in the morning during which the sky is light but the Sun is not yet visible. The beginning of morning twilight is called dawn. The time of Sunset is defined in astronomy as the moment when the trailing edge of the Sun's disk disappears below the horizon. The period between Sunset and dusk is also called twilight.
Civil twilight is when the Sun is 6 degrees under the horizon or what they call objects are distinguishable and some stars and planets are visible to the naked eye. Nautical twilight is when the Sun is 12 degrees under the horizon or what they call objects are no longer distinguishable, and the horizon is no longer visible to the naked eye. Astronomical twilight is when the Sun is 18 degrees under the horizon or what they call the Sun no longer illuminates the sky, and thus no longer interferes with astronomical observations.
The light from the Sun is refracted as it passes through the Earth's atmosphere. The Sun is still visible after it is geometrically below the horizon. Refraction also affects the apparent shape of the Sun when it is very close to the horizon. It looks like the Sun is higher in the sky than it really is. Light from the bottom edge of the Sun's disk is refracted more than light from the top, since refraction increases as the angle of elevation decreases. This raises the apparent position of the bottom edge more than the top, reducing the apparent height of the solar disk. Its width is unaltered, so the disk appears wider than it is high. The Sun also appears larger on the horizon which is an optical illusion and similar to the Moon illusion. For example with a Super Moon.
Eclipses - the Moon and the Sun
The Moon is able to cover the Sun’s disc precisely because the Sun is about 400 times bigger than the Moon, and also about 400 times further away, meaning they have the same size in our sky. It is such a coincidence! When the Moon is "near" to the Sun. It’s all a question of orbits. Earth orbits the Sun along a plane that we call the ecliptic. All of the planets orbit more or less along this plane. The Moon orbits Earth at an angle that is tilted with about 5 degrees to the ecliptic. This means that on each orbit around Earth (a lunar orbit lasts 27 days), the Moon only crosses the ecliptic at two locations and these are the only two opportunities for an eclipse, be it a solar or a lunar eclipse.
Below shows the angular sizes of a few objects in the sky as seen from the Earth:
Celestial body Angular diameter or size
Sun 31′31″ – 32′33″
Moon 29′20″ – 34′6″
Helix Nebula about 16′ by 28′
Spire in Eagle Nebula 4′40″
Venus 9.67″ – 63.00″
Jupiter 29.80″ – 49.06″
Saturn 14.50″ – 19.92″
Mars 3.50″ – 25.08″
Mercury 4.54″ – 13.02″
Uranus 3.31″ – 4.04″
Neptune 2.17″ – 2.36″
Ceres 0.33″ – 0.84″
Vesta 0.20″ – 0.64″
Pluto 0.063″ – 0.115″
R Doradus 0.052″ – 0.062″
Betelgeuse 0.049″ – 0.060″
Eris 0.034″ – 0.089″
Alpha Centauri A 0.007″
Proxima Centauri 0.001″
The International Space Station (ISS) is the queen of the satellites. The actual dimensions of ISS are 109 m x 73 m x 27.5 m or about the size of a football filed. In the night sky the angular size of ISS is depending on the orientation. The maximum angular size is 1' or 60".
The Sun is 30 to31 times the maximum value for Venus being 1891–1953″
The Moon is 28 to 32.5 times the maximum value for Venus being 1760–2046″
The Sun is about 250000 times that of Sirius (Sirius has twice the diameter and its distance is 500000 times as much)
The Sun is also about 250000 times that of Alpha Centauri A (it has about the same diameter and the distance is 250000 times as much
The Sun is about the same as that of the Moon (the Sun's diameter is 400 times as large and its distance also)
How much sky does an arc second takes up? Pull a hair from your head and hold it at arm's length. The width of that hair covers one arc second of the sky.
While angular sizes measured in degrees are useful for larger patches of sky. In the constellation of Orion for example, the three stars of the belt cover about 4.5 degrees of angular size. Distances between celestial objects as they appear to us on the sky can be measured with angles and degrees. For example, you might say something like: The Moon was three degrees from a certain star in the sky.
The boundaries of Canis Major or the Big Dipper constellation is about 389 square degrees large, while Canis Minor, with Polaris or the Pole Star is 183 square degrees large. Constellations are not real objects. The stars and other bright objects that make them are not connected in any way. We just pretend that they make a pattern in the sky based on how they line up when we look at them. The pattern they form may take the shape of an animal, a mythological creature, a man, a woman, or an inanimate object such as a microscope, a compass, or a crown.
The largest constellation by area is Hydra which is 3.16% of the sky
The smallest is Crux which only takes up 0.17 percent of the sky
Small patterns of stars within a constellation are called asterisms - these include the Big Dipper and Little Dipper
The word "constellation" comes from a Latin term meaning "set with stars."
Twenty two different constellation names start with the letter "C"